New strain states and radical property tuning of metal oxides using a nanocomposite thin film approach

Abstract

Auxetic-like strain states were generated in self-assembled nanocomposite thin films of (Ba 0.6 Sr 0.4 TiO 3) 1-x - (Sm 2 O 3) x (BSTO - SmO). A switch from auxetic-like to elastic-like strain behavior was observed for x > 0.50, when the SmO switched from being nanopillars in the BSTO matrix to being the matrix with BSTO nanopillars embedded in it. A simple model was adopted to explain how in-plane strain varies with x. At high x (0.75), strongly enhanced ferroelectric properties were obtained compared to pure BSTO films. The nanocomposite method represents a powerful new way to tune the properties of a wide range of strongly correlated metal oxides whose properties are very sensitive to strain.